Imaging of the Lung 1 Flashcards
Will an AP CXR or a PA CXR have a bigger distortion of heart size?
AP CXR will have a bigger distortion of the heart size. When imaging the heart, you want the heart to be as close as possible to the film so that when the x-rays pass through, there isn’t distance for them to spread/magnify.
What are left and right lateral decubitus positions?
Left lateral decubitus is when the patient has their left side down and right lateral decubitus is when the patient has their right side down. This is useful for checking pleural effusion and pneumothorax.
If you’re concerned about a right pneumothorax, would you have the patient in left lateral decubitus or right lateral decubitus for the image?
Left lateral decubitus. Air ascends so if you have the left side down, the air will ascend and you can better check for the right sided pneumothorax
If you’re concerned about a right sided pleural effusion, would you have the patient in right or left lateral decubitus?
Right lateral decubitus. Fluid falls because of gravity so if you have the patient in right lateral decubitus, the fluid will fall and you can better check for the right sided pleural effusion.
What’s going on here?
This patient has a pleural effusion on their right side. The patient was put in the right lateral decubitus position and that allowed us to see that there is free flow of fluid along the right hemithorax.
List things that you might see in an X-ray from lowest density to highest density.
Lowest density is Air (black)
then fat
then soft tissue, muscle, tendon, ligaments, blood, and water
then Bone/calcium
then Metal
C. Metal
It’s much whiter than bone.
D. Need a lateral view
“one view is no view”
What’s being explained here?
In radiology, the silhouette sign refers to the loss of normal borders between thoracic structures. It is usually caused by an intrathoracic radiopaque mass that touches the border of the heart or aorta. In other words, it is difficult to make out the borders of a particular structure - normal or otherwise - because it is next to another dense structure, both of which will appear white on a standard X-ray. It may occur, for example, in right middle lobe syndrome, where the right heart margin is obscured, and in right lower lobe pneumonia, where the border of the diaphragm on the right side is obscured, while the right heart margin remains distinct. Silhouette sign is very useful in localizing lung lesions as all structures forming cardiac silhouette are in contact with a specific portion of the lung.
What’s going on here?
The border of the right heart is unclear. This indicates that there is a pneumonia in the right middle lobe.
What’s going on here?
You can still see the left border of the heart but you cannot see the diaphragmatic silhouette. This is indicative of a left lower lobe pneumonia because the lower lobe is immediately adjacent to the diaphragm.
In x-rays, when is there loss of borders?
Loss of borders happens when two structures of similar density come into contact.
What is being illustrated here?
Overexposed X-rays appear darker than normal and underexposed X-rays appear lighter. The x-ray on the left is overexposed and the one on the right is underexposed. Neither is ideal for looking for pathologies.
How can you tell if a CXR has proper exposure?
The rule of thumb is that you should be able to faintly see the vertebral bodies behind the mediastinum in a properly exposed CXR.
How can you tell if an X-ray is rotated?
You look at the clavicles bilaterally to make sure that they are equidistant from the center of the spine.
What’s the issue with this image?
The image is rotated. You can see that the center of the spine is much closer to the left clavicle than the right clavicle. This causes an obvious distortion and shift of the cardiac silhouette.
What’s the issue here?
These are two pictures of the same patient. On the left x-ray, the patient didn’t take a sufficient breath for the X-ray. You can see that the diaphragm is higher up (you can count less ribs). This causes haziness in the lower lobes due to crowding of vessels. This can give a false positive read for disease.
It is important for patients to take an adequate breath for the CXR to be accurate.
When you lose the right heart border in a CXR due to airspace opacity, which lobe can you localize the problem to?
Right middle lobe.
The right middle lobe and right upper lobe are anterior structures compared to the lower lobes so loss of the right heart border is due to the anterior structure in the area (right middle lobe).
A problem in which lobe of the lung would cause a loss of the diaphragm border?
Lower lobe. The lower lobes of both the right and left lungs border the diaphragm. So, if there is fluid within the lung, you will lose the border of the diaphragm.
If there is a loss of clarity in the left heart border, which lung lobe are you concerned about?
The lingula of the left upper lobe.
Remember that the upper lobe is posterior to the heart and causes an issue with imaging the diaphragm border but the upper lobe is in front of the heart and causes issues with clarity in the heart border.
Where is the abnormality?
A. Lingula
B. Right middle lobe
C. Left lower lobe
C. Left lower lobe
There is a loss of the left diaphragmatic border which indicates a left lower lobe problem.
In the left image, there is an abnormality in the left lower lobe because the left border of the diaphragm is lost. What is important about getting the lateral CXR (on the right) when imaging lower lobes?
Much of the lower lobes is actually inferior and posterior compared to the upper lobes which are anterior and superior. So, when looking at the lower lobes, there is a significant portion of the lung that is obscured by the the diaphragm. So, in order to get a full look at the lower lobes, you need to get a lateral view. On the lateral view, if you look at the spine, you can see that the vertebral bodies get more white as you follow them down. The vertebral bodies shouldn’t be getting more dense–this is a clue to you that there is lower lobe issue.
This is called the “spine sign”
In a normal trachea, there is a slight right-ward course. Why?
On the left of the trachea, there is the aortic arch which pushes against the trachea to cause it to take a slight right-ward course. This is normal.
Where is the endotracheal tube heading?
A. Esophagus
B. Distal trachea
C. Right mainstem bronchus
C. Right mainstem bronchus
You can see that it passes the carina and heads into the right mainstem bronchus.
The esophagus is typically a bit to the left (more centered) because the trachea has the natural curve to the right due to the aortic arch pushing it to the right. If the endotracheal tube was in the esophagus, you would see it to the left of the trachea.
A feeding tube was placed. Was it placed correctly?
No. It was not.
Where are the normal borders/bumps of the heart and what anatomical landmarks do they illustrate?
Is there a cardiomediastinal silhouette abnormality here?
A. Right
B. Left
C. Normal
A. Right.
There is one too many lines in the right side of the cardiomediastinal silhouette.
This is a very dilated, abnormal esophagus. This is caused by Achalasia (a disorder making it difficult for food and liquid to pass into the stomach)
What’s the issue here?
The main pulmonary artery is enlarged.
This can be a sign of pulmonary artery hypertension, shunt with left to right flow, thromboembolic disease (usually not in acute cases), etc.
What is a radiographic sign that you will see in normal pleura?
Sharp costophrenic sulci
What is the issue here?
The costophrenic sulci are blunted (not sharp). This is a sign of pleural effusion.
Also seen in this patient are abnormal densities throughout the lungs. Since there are darker spots within lighter spots, you can tell that these areas have had infarction and necrosis (cavitary leasions).
What’s going on here?
A. Pleural effusion
B. Pleural nodularity
C. Pneumothorax
D. Pleural effusion and nodularity
D. pleural effusion and nodularity
The fluid obeys gravity and creates the horizontal meniscus in the right lung field. However, on the lateral side of the pleura, there are nodules that poke inwards. These are not effusion as they do not obey gravitiy–these are nodules (soft tissue) which are a sign of malignancy.
On a CXR, what indicates a pneumothorax?
A clear pleural line and a lack of vessels that go all the way to the chest walls.
This is a significant finding that should be reported immediately.
What radiologic finding can be a false positive for pneumothorax?
Skin folds.
In the left image, you can see that the patient has a left sided pneumothorax. In the right image, you can see that there is a skin fold that could be mistaken as a pneumothorax. You can tell that it is a skin fold because it continues down past the diaphragm. Also, between the skin fold and the chest wall, there is still vasculature which would be clear if it was actually a pneumothorax.
Which rib is anterior and which is posterior?
The red rib is the posterior rib and the blue rib is the anterior rib.
Posterior ribs are more horizontal as they go back and attach to the thoracic spine on consecutive levels. The anterior ribs are more curved as they make their way to attach on the sternum.
